// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
package xyz.noark.asm;

/**
 * A visitor to visit a Java method. The methods of this class must be called in
 * the following order: ( {@code visitParameter} )* [
 * {@code visitAnnotationDefault} ] ( {@code visitAnnotation} |
 * {@code visitAnnotableParameterCount} | {@code visitParameterAnnotation}
 * {@code
 * visitTypeAnnotation} | {@code visitAttribute} )* [ {@code visitCode} (
 * {@code visitFrame} | {@code visit<i>X</i>Insn} | {@code visitLabel} |
 * {@code visitInsnAnnotation} | {@code
 * visitTryCatchBlock} | {@code visitTryCatchAnnotation} |
 * {@code visitLocalVariable} | {@code
 * visitLocalVariableAnnotation} | {@code visitLineNumber} )* {@code visitMaxs}
 * ] {@code visitEnd}. In addition, the {@code visit<i>X</i>Insn} and
 * {@code visitLabel} methods must be called in the sequential order of the
 * bytecode instructions of the visited code, {@code visitInsnAnnotation} must
 * be called <i>after</i> the annotated instruction, {@code visitTryCatchBlock}
 * must be called <i>before</i> the labels passed as arguments have been
 * visited, {@code
 * visitTryCatchBlockAnnotation} must be called <i>after</i> the corresponding
 * try catch block has been visited, and the {@code visitLocalVariable},
 * {@code visitLocalVariableAnnotation} and {@code
 * visitLineNumber} methods must be called <i>after</i> the labels passed as
 * arguments have been visited.
 *
 * @author Eric Bruneton
 */
public abstract class MethodVisitor {

	private static final String REQUIRES_ASM5 = "This feature requires ASM5";

	/**
	 * The ASM API version implemented by this visitor. The value of this field
	 * must be one of {@link Opcodes#ASM4}, {@link Opcodes#ASM5},
	 * {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
	 */
	protected final int api;

	/**
	 * The method visitor to which this visitor must delegate method calls. May
	 * be null.
	 */
	protected MethodVisitor mv;

	/**
	 * Constructs a new {@link MethodVisitor}.
	 *
	 * @param api the ASM API version implemented by this visitor. Must be one
	 *            of {@link Opcodes#ASM4}, {@link Opcodes#ASM5},
	 *            {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
	 */
	public MethodVisitor(final int api) {
		this(api, null);
	}

	/**
	 * Constructs a new {@link MethodVisitor}.
	 *
	 * @param api the ASM API version implemented by this visitor. Must be one
	 *            of {@link Opcodes#ASM4}, {@link Opcodes#ASM5},
	 *            {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
	 * @param methodVisitor the method visitor to which this visitor must
	 *            delegate method calls. May be null.
	 */
	public MethodVisitor(final int api, final MethodVisitor methodVisitor) {
		if (api != Opcodes.ASM7 && api != Opcodes.ASM6 && api != Opcodes.ASM5 && api != Opcodes.ASM4) {
			throw new IllegalArgumentException("Unsupported api " + api);
		}
		this.api = api;
		this.mv = methodVisitor;
	}

	// -----------------------------------------------------------------------------------------------
	// Parameters, annotations and non standard attributes
	// -----------------------------------------------------------------------------------------------

	/**
	 * Visits a parameter of this method.
	 *
	 * @param name parameter name or null if none is provided.
	 * @param access the parameter's access flags, only {@code ACC_FINAL},
	 *            {@code ACC_SYNTHETIC} or/and {@code ACC_MANDATED} are allowed
	 *            (see {@link Opcodes}).
	 */
	public void visitParameter(final String name, final int access) {
		if (api < Opcodes.ASM5) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (mv != null) {
			mv.visitParameter(name, access);
		}
	}

	/**
	 * Visits the default value of this annotation interface method.
	 *
	 * @return a visitor to the visit the actual default value of this
	 *         annotation interface method, or {@literal null} if this visitor
	 *         is not interested in visiting this default value. The 'name'
	 *         parameters passed to the methods of this annotation visitor are
	 *         ignored. Moreover, exacly one visit method must be called on this
	 *         annotation visitor, followed by visitEnd.
	 */
	public AnnotationVisitor visitAnnotationDefault() {
		if (mv != null) {
			return mv.visitAnnotationDefault();
		}
		return null;
	}

	/**
	 * Visits an annotation of this method.
	 *
	 * @param descriptor the class descriptor of the annotation class.
	 * @param visible {@literal true} if the annotation is visible at runtime.
	 * @return a visitor to visit the annotation values, or {@literal null} if
	 *         this visitor is not interested in visiting this annotation.
	 */
	public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
		if (mv != null) {
			return mv.visitAnnotation(descriptor, visible);
		}
		return null;
	}

	/**
	 * Visits an annotation on a type in the method signature.
	 *
	 * @param typeRef a reference to the annotated type. The sort of this type
	 *            reference must be {@link TypeReference#METHOD_TYPE_PARAMETER},
	 *            {@link TypeReference#METHOD_TYPE_PARAMETER_BOUND},
	 *            {@link TypeReference#METHOD_RETURN},
	 *            {@link TypeReference#METHOD_RECEIVER},
	 *            {@link TypeReference#METHOD_FORMAL_PARAMETER} or
	 *            {@link TypeReference#THROWS}. See {@link TypeReference}.
	 * @param typePath the path to the annotated type argument, wildcard bound,
	 *            array element type, or static inner type within 'typeRef'. May
	 *            be {@literal null} if the annotation targets 'typeRef' as a
	 *            whole.
	 * @param descriptor the class descriptor of the annotation class.
	 * @param visible {@literal true} if the annotation is visible at runtime.
	 * @return a visitor to visit the annotation values, or {@literal null} if
	 *         this visitor is not interested in visiting this annotation.
	 */
	public AnnotationVisitor visitTypeAnnotation(final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
		if (api < Opcodes.ASM5) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (mv != null) {
			return mv.visitTypeAnnotation(typeRef, typePath, descriptor, visible);
		}
		return null;
	}

	/**
	 * Visits the number of method parameters that can have annotations. By
	 * default (i.e. when this method is not called), all the method parameters
	 * defined by the method descriptor can have annotations.
	 *
	 * @param parameterCount the number of method parameters than can have
	 *            annotations. This number must be less or equal than the number
	 *            of parameter types in the method descriptor. It can be
	 *            strictly less when a method has synthetic parameters and when
	 *            these parameters are ignored when computing parameter indices
	 *            for the purpose of parameter annotations (see
	 *            https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
	 * @param visible {@literal true} to define the number of method parameters
	 *            that can have annotations visible at runtime, {@literal false}
	 *            to define the number of method parameters that can have
	 *            annotations invisible at runtime.
	 */
	public void visitAnnotableParameterCount(final int parameterCount, final boolean visible) {
		if (mv != null) {
			mv.visitAnnotableParameterCount(parameterCount, visible);
		}
	}

	/**
	 * Visits an annotation of a parameter this method.
	 *
	 * @param parameter the parameter index. This index must be strictly smaller
	 *            than the number of parameters in the method descriptor, and
	 *            strictly smaller than the parameter count specified in
	 *            {@link #visitAnnotableParameterCount}. Important note: <i>a
	 *            parameter index i is not required to correspond to the i'th
	 *            parameter descriptor in the method descriptor</i>, in
	 *            particular in case of synthetic parameters (see
	 *            https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
	 * @param descriptor the class descriptor of the annotation class.
	 * @param visible {@literal true} if the annotation is visible at runtime.
	 * @return a visitor to visit the annotation values, or {@literal null} if
	 *         this visitor is not interested in visiting this annotation.
	 */
	public AnnotationVisitor visitParameterAnnotation(final int parameter, final String descriptor, final boolean visible) {
		if (mv != null) {
			return mv.visitParameterAnnotation(parameter, descriptor, visible);
		}
		return null;
	}

	/**
	 * Visits a non standard attribute of this method.
	 *
	 * @param attribute an attribute.
	 */
	public void visitAttribute(final Attribute attribute) {
		if (mv != null) {
			mv.visitAttribute(attribute);
		}
	}

	/**
	 * Starts the visit of the method's code, if any (i.e. non abstract method).
	 */
	public void visitCode() {
		if (mv != null) {
			mv.visitCode();
		}
	}

	/**
	 * Visits the current state of the local variables and operand stack
	 * elements. This method must(*) be called <i>just before</i> any
	 * instruction <b>i</b> that follows an unconditional branch instruction
	 * such as GOTO or THROW, that is the target of a jump instruction, or that
	 * starts an exception handler block. The visited types must describe the
	 * values of the local variables and of the operand stack elements <i>just
	 * before</i> <b>i</b> is executed.<br>
	 * <br>
	 * (*) this is mandatory only for classes whose version is greater than or
	 * equal to {@link Opcodes#V1_6}. <br>
	 * <br>
	 * The frames of a method must be given either in expanded form, or in
	 * compressed form (all frames must use the same format, i.e. you must not
	 * mix expanded and compressed frames within a single method):
	 *
	 * <ul>
	 * <li>In expanded form, all frames must have the F_NEW type.
	 * <li>In compressed form, frames are basically "deltas" from the state of
	 * the previous frame:
	 * <ul>
	 * <li>{@link Opcodes#F_SAME} representing frame with exactly the same
	 * locals as the previous frame and with the empty stack.
	 * <li>{@link Opcodes#F_SAME1} representing frame with exactly the same
	 * locals as the previous frame and with single value on the stack (
	 * <code>numStack</code> is 1 and <code>stack[0]</code> contains value for
	 * the type of the stack item).
	 * <li>{@link Opcodes#F_APPEND} representing frame with current locals are
	 * the same as the locals in the previous frame, except that additional
	 * locals are defined (<code>
	 *             numLocal</code> is 1, 2 or 3 and <code>local</code> elements
	 * contains values representing added types).
	 * <li>{@link Opcodes#F_CHOP} representing frame with current locals are the
	 * same as the locals in the previous frame, except that the last 1-3 locals
	 * are absent and with the empty stack (<code>numLocal</code> is 1, 2 or 3).
	 * <li>{@link Opcodes#F_FULL} representing complete frame data.
	 * </ul>
	 * </ul>
	 *
	 * <br>
	 * In both cases the first frame, corresponding to the method's parameters
	 * and access flags, is implicit and must not be visited. Also, it is
	 * illegal to visit two or more frames for the same code location (i.e., at
	 * least one instruction must be visited between two calls to visitFrame).
	 *
	 * @param type the type of this stack map frame. Must be
	 *            {@link Opcodes#F_NEW} for expanded frames, or
	 *            {@link Opcodes#F_FULL}, {@link Opcodes#F_APPEND},
	 *            {@link Opcodes#F_CHOP}, {@link Opcodes#F_SAME} or
	 *            {@link Opcodes#F_APPEND}, {@link Opcodes#F_SAME1} for
	 *            compressed frames.
	 * @param numLocal the number of local variables in the visited frame.
	 * @param local the local variable types in this frame. This array must not
	 *            be modified. Primitive types are represented by
	 *            {@link Opcodes#TOP}, {@link Opcodes#INTEGER},
	 *            {@link Opcodes#FLOAT}, {@link Opcodes#LONG},
	 *            {@link Opcodes#DOUBLE}, {@link Opcodes#NULL} or
	 *            {@link Opcodes#UNINITIALIZED_THIS} (long and double are
	 *            represented by a single element). Reference types are
	 *            represented by String objects (representing internal names),
	 *            and uninitialized types by Label objects (this label
	 *            designates the NEW instruction that created this uninitialized
	 *            value).
	 * @param numStack the number of operand stack elements in the visited
	 *            frame.
	 * @param stack the operand stack types in this frame. This array must not
	 *            be modified. Its content has the same format as the "local"
	 *            array.
	 * @throws IllegalStateException if a frame is visited just after another
	 *             one, without any instruction between the two (unless this
	 *             frame is a Opcodes#F_SAME frame, in which case it is silently
	 *             ignored).
	 */
	public void visitFrame(final int type, final int numLocal, final Object[] local, final int numStack, final Object[] stack) {
		if (mv != null) {
			mv.visitFrame(type, numLocal, local, numStack, stack);
		}
	}

	// -----------------------------------------------------------------------------------------------
	// Normal instructions
	// -----------------------------------------------------------------------------------------------

	/**
	 * Visits a zero operand instruction.
	 *
	 * @param opcode the opcode of the instruction to be visited. This opcode is
	 *            either NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1,
	 *            ICONST_2, ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1,
	 *            FCONST_0, FCONST_1, FCONST_2, DCONST_0, DCONST_1, IALOAD,
	 *            LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD,
	 *            IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE,
	 *            SASTORE, POP, POP2, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1,
	 *            DUP2_X2, SWAP, IADD, LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB,
	 *            IMUL, LMUL, FMUL, DMUL, IDIV, LDIV, FDIV, DDIV, IREM, LREM,
	 *            FREM, DREM, INEG, LNEG, FNEG, DNEG, ISHL, LSHL, ISHR, LSHR,
	 *            IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, I2L, I2F, I2D,
	 *            L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, I2C, I2S,
	 *            LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IRETURN, LRETURN, FRETURN,
	 *            DRETURN, ARETURN, RETURN, ARRAYLENGTH, ATHROW, MONITORENTER,
	 *            or MONITOREXIT.
	 */
	public void visitInsn(final int opcode) {
		if (mv != null) {
			mv.visitInsn(opcode);
		}
	}

	/**
	 * Visits an instruction with a single int operand.
	 *
	 * @param opcode the opcode of the instruction to be visited. This opcode is
	 *            either BIPUSH, SIPUSH or NEWARRAY.
	 * @param operand the operand of the instruction to be visited.<br>
	 *            When opcode is BIPUSH, operand value should be between
	 *            Byte.MIN_VALUE and Byte.MAX_VALUE. <br>
	 *            When opcode is SIPUSH, operand value should be between
	 *            Short.MIN_VALUE and Short.MAX_VALUE. <br>
	 *            When opcode is NEWARRAY, operand value should be one of
	 *            {@link Opcodes#T_BOOLEAN}, {@link Opcodes#T_CHAR},
	 *            {@link Opcodes#T_FLOAT}, {@link Opcodes#T_DOUBLE},
	 *            {@link Opcodes#T_BYTE}, {@link Opcodes#T_SHORT},
	 *            {@link Opcodes#T_INT} or {@link Opcodes#T_LONG}.
	 */
	public void visitIntInsn(final int opcode, final int operand) {
		if (mv != null) {
			mv.visitIntInsn(opcode, operand);
		}
	}

	/**
	 * Visits a local variable instruction. A local variable instruction is an
	 * instruction that loads or stores the value of a local variable.
	 *
	 * @param opcode the opcode of the local variable instruction to be visited.
	 *            This opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD,
	 *            ISTORE, LSTORE, FSTORE, DSTORE, ASTORE or RET.
	 * @param var the operand of the instruction to be visited. This operand is
	 *            the index of a local variable.
	 */
	public void visitVarInsn(final int opcode, final int var) {
		if (mv != null) {
			mv.visitVarInsn(opcode, var);
		}
	}

	/**
	 * Visits a type instruction. A type instruction is an instruction that
	 * takes the internal name of a class as parameter.
	 *
	 * @param opcode the opcode of the type instruction to be visited. This
	 *            opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
	 * @param type the operand of the instruction to be visited. This operand
	 *            must be the internal name of an object or array class (see
	 *            {@link Type#getInternalName()}).
	 */
	public void visitTypeInsn(final int opcode, final String type) {
		if (mv != null) {
			mv.visitTypeInsn(opcode, type);
		}
	}

	/**
	 * Visits a field instruction. A field instruction is an instruction that
	 * loads or stores the value of a field of an object.
	 *
	 * @param opcode the opcode of the type instruction to be visited. This
	 *            opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
	 * @param owner the internal name of the field's owner class (see
	 *            {@link Type#getInternalName()}).
	 * @param name the field's name.
	 * @param descriptor the field's descriptor (see {@link Type}).
	 */
	public void visitFieldInsn(final int opcode, final String owner, final String name, final String descriptor) {
		if (mv != null) {
			mv.visitFieldInsn(opcode, owner, name, descriptor);
		}
	}

	/**
	 * Visits a method instruction. A method instruction is an instruction that
	 * invokes a method.
	 *
	 * @param opcode the opcode of the type instruction to be visited. This
	 *            opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or
	 *            INVOKEINTERFACE.
	 * @param owner the internal name of the method's owner class (see
	 *            {@link Type#getInternalName()}).
	 * @param name the method's name.
	 * @param descriptor the method's descriptor (see {@link Type}).
	 * @deprecated use
	 *             {@link #visitMethodInsn(int, String, String, String, boolean)}
	 *             instead.
	 */
	@Deprecated
	public void visitMethodInsn(final int opcode, final String owner, final String name, final String descriptor) {
		int opcodeAndSource = opcode | (api < Opcodes.ASM5 ? Opcodes.SOURCE_DEPRECATED : 0);
		visitMethodInsn(opcodeAndSource, owner, name, descriptor, opcode == Opcodes.INVOKEINTERFACE);
	}

	/**
	 * Visits a method instruction. A method instruction is an instruction that
	 * invokes a method.
	 *
	 * @param opcode the opcode of the type instruction to be visited. This
	 *            opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or
	 *            INVOKEINTERFACE.
	 * @param owner the internal name of the method's owner class (see
	 *            {@link Type#getInternalName()}).
	 * @param name the method's name.
	 * @param descriptor the method's descriptor (see {@link Type}).
	 * @param isInterface if the method's owner class is an interface.
	 */
	public void visitMethodInsn(final int opcode, final String owner, final String name, final String descriptor, final boolean isInterface) {
		if (api < Opcodes.ASM5 && (opcode & Opcodes.SOURCE_DEPRECATED) == 0) {
			if (isInterface != (opcode == Opcodes.INVOKEINTERFACE)) {
				throw new UnsupportedOperationException("INVOKESPECIAL/STATIC on interfaces requires ASM5");
			}
			visitMethodInsn(opcode, owner, name, descriptor);
			return;
		}
		if (mv != null) {
			mv.visitMethodInsn(opcode & ~Opcodes.SOURCE_MASK, owner, name, descriptor, isInterface);
		}
	}

	/**
	 * Visits an invokedynamic instruction.
	 *
	 * @param name the method's name.
	 * @param descriptor the method's descriptor (see {@link Type}).
	 * @param bootstrapMethodHandle the bootstrap method.
	 * @param bootstrapMethodArguments the bootstrap method constant arguments.
	 *            Each argument must be an {@link Integer}, {@link Float},
	 *            {@link Long}, {@link Double}, {@link String}, {@link Type},
	 *            {@link Handle} or {@link ConstantDynamic} value. This method
	 *            is allowed to modify the content of the array so a caller
	 *            should expect that this array may change.
	 */
	public void visitInvokeDynamicInsn(final String name, final String descriptor, final Handle bootstrapMethodHandle, final Object... bootstrapMethodArguments) {
		if (api < Opcodes.ASM5) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (mv != null) {
			mv.visitInvokeDynamicInsn(name, descriptor, bootstrapMethodHandle, bootstrapMethodArguments);
		}
	}

	/**
	 * Visits a jump instruction. A jump instruction is an instruction that may
	 * jump to another instruction.
	 *
	 * @param opcode the opcode of the type instruction to be visited. This
	 *            opcode is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE,
	 *            IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT,
	 *            IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE, GOTO, JSR, IFNULL or
	 *            IFNONNULL.
	 * @param label the operand of the instruction to be visited. This operand
	 *            is a label that designates the instruction to which the jump
	 *            instruction may jump.
	 */
	public void visitJumpInsn(final int opcode, final Label label) {
		if (mv != null) {
			mv.visitJumpInsn(opcode, label);
		}
	}

	/**
	 * Visits a label. A label designates the instruction that will be visited
	 * just after it.
	 *
	 * @param label a {@link Label} object.
	 */
	public void visitLabel(final Label label) {
		if (mv != null) {
			mv.visitLabel(label);
		}
	}

	// -----------------------------------------------------------------------------------------------
	// Special instructions
	// -----------------------------------------------------------------------------------------------

	/**
	 * Visits a LDC instruction. Note that new constant types may be added in
	 * future versions of the Java Virtual Machine. To easily detect new
	 * constant types, implementations of this method should check for
	 * unexpected constant types, like this:
	 *
	 * <pre>
	 * if (cst instanceof Integer) {
	 * 	// ...
	 * } else if (cst instanceof Float) {
	 * 	// ...
	 * } else if (cst instanceof Long) {
	 * 	// ...
	 * } else if (cst instanceof Double) {
	 * 	// ...
	 * } else if (cst instanceof String) {
	 * 	// ...
	 * } else if (cst instanceof Type) {
	 * 	int sort = ((Type) cst).getSort();
	 * 	if (sort == Type.OBJECT) {
	 * 		// ...
	 * 	} else if (sort == Type.ARRAY) {
	 * 		// ...
	 * 	} else if (sort == Type.METHOD) {
	 * 		// ...
	 * 	} else {
	 * 		// throw an exception
	 * 	}
	 * } else if (cst instanceof Handle) {
	 * 	// ...
	 * } else if (cst instanceof ConstantDynamic) {
	 * 	// ...
	 * } else {
	 * 	// throw an exception
	 * }
	 * </pre>
	 *
	 * @param value the constant to be loaded on the stack. This parameter must
	 *            be a non null {@link Integer}, a {@link Float}, a
	 *            {@link Long}, a {@link Double}, a {@link String}, a
	 *            {@link Type} of OBJECT or ARRAY sort for {@code .class}
	 *            constants, for classes whose version is 49, a {@link Type} of
	 *            METHOD sort for MethodType, a {@link Handle} for MethodHandle
	 *            constants, for classes whose version is 51 or a
	 *            {@link ConstantDynamic} for a constant dynamic for classes
	 *            whose version is 55.
	 */
	public void visitLdcInsn(final Object value) {
		if (api < Opcodes.ASM5 && (value instanceof Handle || (value instanceof Type && ((Type) value).getSort() == Type.METHOD))) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (api != Opcodes.ASM7 && value instanceof ConstantDynamic) {
			throw new UnsupportedOperationException("This feature requires ASM7");
		}
		if (mv != null) {
			mv.visitLdcInsn(value);
		}
	}

	/**
	 * Visits an IINC instruction.
	 *
	 * @param var index of the local variable to be incremented.
	 * @param increment amount to increment the local variable by.
	 */
	public void visitIincInsn(final int var, final int increment) {
		if (mv != null) {
			mv.visitIincInsn(var, increment);
		}
	}

	/**
	 * Visits a TABLESWITCH instruction.
	 *
	 * @param min the minimum key value.
	 * @param max the maximum key value.
	 * @param dflt beginning of the default handler block.
	 * @param labels beginnings of the handler blocks. {@code labels[i]} is the
	 *            beginning of the handler block for the {@code min + i} key.
	 */
	public void visitTableSwitchInsn(final int min, final int max, final Label dflt, final Label... labels) {
		if (mv != null) {
			mv.visitTableSwitchInsn(min, max, dflt, labels);
		}
	}

	/**
	 * Visits a LOOKUPSWITCH instruction.
	 *
	 * @param dflt beginning of the default handler block.
	 * @param keys the values of the keys.
	 * @param labels beginnings of the handler blocks. {@code labels[i]} is the
	 *            beginning of the handler block for the {@code keys[i]} key.
	 */
	public void visitLookupSwitchInsn(final Label dflt, final int[] keys, final Label[] labels) {
		if (mv != null) {
			mv.visitLookupSwitchInsn(dflt, keys, labels);
		}
	}

	/**
	 * Visits a MULTIANEWARRAY instruction.
	 *
	 * @param descriptor an array type descriptor (see {@link Type}).
	 * @param numDimensions the number of dimensions of the array to allocate.
	 */
	public void visitMultiANewArrayInsn(final String descriptor, final int numDimensions) {
		if (mv != null) {
			mv.visitMultiANewArrayInsn(descriptor, numDimensions);
		}
	}

	/**
	 * Visits an annotation on an instruction. This method must be called just
	 * <i>after</i> the annotated instruction. It can be called several times
	 * for the same instruction.
	 *
	 * @param typeRef a reference to the annotated type. The sort of this type
	 *            reference must be {@link TypeReference#INSTANCEOF},
	 *            {@link TypeReference#NEW},
	 *            {@link TypeReference#CONSTRUCTOR_REFERENCE},
	 *            {@link TypeReference#METHOD_REFERENCE},
	 *            {@link TypeReference#CAST},
	 *            {@link TypeReference#CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT},
	 *            {@link TypeReference#METHOD_INVOCATION_TYPE_ARGUMENT},
	 *            {@link TypeReference#CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT}, or
	 *            {@link TypeReference#METHOD_REFERENCE_TYPE_ARGUMENT}. See
	 *            {@link TypeReference}.
	 * @param typePath the path to the annotated type argument, wildcard bound,
	 *            array element type, or static inner type within 'typeRef'. May
	 *            be {@literal null} if the annotation targets 'typeRef' as a
	 *            whole.
	 * @param descriptor the class descriptor of the annotation class.
	 * @param visible {@literal true} if the annotation is visible at runtime.
	 * @return a visitor to visit the annotation values, or {@literal null} if
	 *         this visitor is not interested in visiting this annotation.
	 */
	public AnnotationVisitor visitInsnAnnotation(final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
		if (api < Opcodes.ASM5) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (mv != null) {
			return mv.visitInsnAnnotation(typeRef, typePath, descriptor, visible);
		}
		return null;
	}

	// -----------------------------------------------------------------------------------------------
	// Exceptions table entries, debug information, max stack and max locals
	// -----------------------------------------------------------------------------------------------

	/**
	 * Visits a try catch block.
	 *
	 * @param start the beginning of the exception handler's scope (inclusive).
	 * @param end the end of the exception handler's scope (exclusive).
	 * @param handler the beginning of the exception handler's code.
	 * @param type the internal name of the type of exceptions handled by the
	 *            handler, or {@literal
	 *     null} to catch any exceptions (for "finally" blocks).
	 * @throws IllegalArgumentException if one of the labels has already been
	 *             visited by this visitor (by the {@link #visitLabel} method).
	 */
	public void visitTryCatchBlock(final Label start, final Label end, final Label handler, final String type) {
		if (mv != null) {
			mv.visitTryCatchBlock(start, end, handler, type);
		}
	}

	/**
	 * Visits an annotation on an exception handler type. This method must be
	 * called <i>after</i> the {@link #visitTryCatchBlock} for the annotated
	 * exception handler. It can be called several times for the same exception
	 * handler.
	 *
	 * @param typeRef a reference to the annotated type. The sort of this type
	 *            reference must be {@link TypeReference#EXCEPTION_PARAMETER}.
	 *            See {@link TypeReference}.
	 * @param typePath the path to the annotated type argument, wildcard bound,
	 *            array element type, or static inner type within 'typeRef'. May
	 *            be {@literal null} if the annotation targets 'typeRef' as a
	 *            whole.
	 * @param descriptor the class descriptor of the annotation class.
	 * @param visible {@literal true} if the annotation is visible at runtime.
	 * @return a visitor to visit the annotation values, or {@literal null} if
	 *         this visitor is not interested in visiting this annotation.
	 */
	public AnnotationVisitor visitTryCatchAnnotation(final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
		if (api < Opcodes.ASM5) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (mv != null) {
			return mv.visitTryCatchAnnotation(typeRef, typePath, descriptor, visible);
		}
		return null;
	}

	/**
	 * Visits a local variable declaration.
	 *
	 * @param name the name of a local variable.
	 * @param descriptor the type descriptor of this local variable.
	 * @param signature the type signature of this local variable. May be
	 *            {@literal null} if the local variable type does not use
	 *            generic types.
	 * @param start the first instruction corresponding to the scope of this
	 *            local variable (inclusive).
	 * @param end the last instruction corresponding to the scope of this local
	 *            variable (exclusive).
	 * @param index the local variable's index.
	 * @throws IllegalArgumentException if one of the labels has not already
	 *             been visited by this visitor (by the {@link #visitLabel}
	 *             method).
	 */
	public void visitLocalVariable(final String name, final String descriptor, final String signature, final Label start, final Label end, final int index) {
		if (mv != null) {
			mv.visitLocalVariable(name, descriptor, signature, start, end, index);
		}
	}

	/**
	 * Visits an annotation on a local variable type.
	 *
	 * @param typeRef a reference to the annotated type. The sort of this type
	 *            reference must be {@link TypeReference#LOCAL_VARIABLE} or
	 *            {@link TypeReference#RESOURCE_VARIABLE}. See
	 *            {@link TypeReference}.
	 * @param typePath the path to the annotated type argument, wildcard bound,
	 *            array element type, or static inner type within 'typeRef'. May
	 *            be {@literal null} if the annotation targets 'typeRef' as a
	 *            whole.
	 * @param start the fist instructions corresponding to the continuous ranges
	 *            that make the scope of this local variable (inclusive).
	 * @param end the last instructions corresponding to the continuous ranges
	 *            that make the scope of this local variable (exclusive). This
	 *            array must have the same size as the 'start' array.
	 * @param index the local variable's index in each range. This array must
	 *            have the same size as the 'start' array.
	 * @param descriptor the class descriptor of the annotation class.
	 * @param visible {@literal true} if the annotation is visible at runtime.
	 * @return a visitor to visit the annotation values, or {@literal null} if
	 *         this visitor is not interested in visiting this annotation.
	 */
	public AnnotationVisitor visitLocalVariableAnnotation(final int typeRef, final TypePath typePath, final Label[] start, final Label[] end, final int[] index, final String descriptor, final boolean visible) {
		if (api < Opcodes.ASM5) {
			throw new UnsupportedOperationException(REQUIRES_ASM5);
		}
		if (mv != null) {
			return mv.visitLocalVariableAnnotation(typeRef, typePath, start, end, index, descriptor, visible);
		}
		return null;
	}

	/**
	 * Visits a line number declaration.
	 *
	 * @param line a line number. This number refers to the source file from
	 *            which the class was compiled.
	 * @param start the first instruction corresponding to this line number.
	 * @throws IllegalArgumentException if {@code start} has not already been
	 *             visited by this visitor (by the {@link #visitLabel} method).
	 */
	public void visitLineNumber(final int line, final Label start) {
		if (mv != null) {
			mv.visitLineNumber(line, start);
		}
	}

	/**
	 * Visits the maximum stack size and the maximum number of local variables
	 * of the method.
	 *
	 * @param maxStack maximum stack size of the method.
	 * @param maxLocals maximum number of local variables for the method.
	 */
	public void visitMaxs(final int maxStack, final int maxLocals) {
		if (mv != null) {
			mv.visitMaxs(maxStack, maxLocals);
		}
	}

	/**
	 * Visits the end of the method. This method, which is the last one to be
	 * called, is used to inform the visitor that all the annotations and
	 * attributes of the method have been visited.
	 */
	public void visitEnd() {
		if (mv != null) {
			mv.visitEnd();
		}
	}
}
